The percentage of total haemoglobin (Hb) that is glycated is widely regarded as an important tool in diabetes management, because it provides an indirect measure of the mean blood glucose concentration over the previous 2-3 months. One of the three main methods available for assaying glycated Hb relies on boronate affinity. In this method glycohaemoglobin can be separated from non-glycohaemoglobin through condensation of solid-phase dihydroxyboronate with the cis-diols present on the sugar moieties of glycohaemoglobin. This method is specific for all glycohaemoglobins which is an advantage over other methods, which rely on separation based on differences in net charge.
However, although the boronate method has certain advantages, it remains an assay which requires laboratory facilities and quite complicated equipment. In particular, the need to determine the percentage of glycated Hb present means that two assay results need to obtained and a comparison made. It is the case that rapid diagnostic assays have been developed, and continue to be developed, which make use of "simple" easy to use diagnostic devices, which can be used either by a subject in their own home, or by a subject's own doctor in the surgery. One example of such a test device is that marketed by Cortecs Diagnostics as HELISAL.RTM.ONE-STEP, which is for the detection of H. pylori infection. The principle of this device is, however, generally applicable to a range of assays. The device consists of two parts, a sample collector and a second part containing an assay strip. The collector is used to collect a sample (of blood in the case of HELISAL.RTM.ONE-STEP) and the collector is then inserted into the second part, with which is interconnects, to release the sample to an assay strip. The sample travels along the strip through various "zones" which contain various reagents, including a coloured label (blue latex particles). If antibodies to H. pylori are present then the label concentrates in a detection zone. The specifics of this particular assay are not important, however. The essential features which are common to this type of assay and which allow its use in their home or doctor's surgery are the ease of sample collection and handling as well as the simplicity in initiating the reaction and the speed with which the result is obtained. Such one-step devices can be utilised in the measurement of glycated Hb but only if the assay method can incorporate the necessary sample treatment to allow comparison of total protein with glycated protein.